Diaphragm centering means



Sept.- 25, 1934. F. GABBERT DIAPHRAGM CENTERING MEANS Filed Jan. 26, 1932 INVENTOR FRITZ GABBERT BY -kg I. mw

ATTORNEY Patented Sept. 25, 1934 UETEEE STATES PATENT GFFECE IAPHRAGIVI CENTERING MEANS Germany Application January 26, 1932, Serial No. 588,302 In Germany December 20, 1930 2 Claims. (Cl. 179115.5)

One object of the invention consists of a centering means for the diaphragm of a sound converter or for the oscillation coil in electrodynamic loudspeakers; to be more precise, the invention concerns centering means in which the parts adapted to secure centering are attached at parts of the magnetic system or the casing located outside the oscillation coil.

A further object is to provide a centering means all parts of which lie in one plane. This makes for low cost of production, ease of manufacture and facility of assembly with its diaphragm. Other objects of the invention will become apparent as the description thereof proceeds.

Centering means of this kind, basically speaking, are known, for instance, in this form that a metallic ring with a crimped border is press-fitted onto the body of the coil, lugs of insulation or yielding non-magnetic metal being connected with the edge or rim which are screwed fast onto the outer poles. Now, this embodiment quite apart from the difiiculties attendant upon manufacture, involves the shortcoming that the lugs after a short while work loose from the metallic edge and result in clinking noises.

Now, according to this invention these drawbacks are obviated by that the centering means consists of a uniform planar part which is punched out in a simple manner either from a sheet of insulation material or a plate of non-magnetic metal. The device consists of an annular ring or part presenting preferably three lugs spaced 120 degrees apart and being bent outwardly, and these lugs are attached to projections on the outer pole piece or the casing in which the diaphragm is housed.

The narrow base end of the truncated-cone diaphragm presents slits through which the lugs of the centering means are stuck. Diaphragm and ring may be connected by pasting or cementing or in any other desired manner.

Referring to the drawing, Figs. 1 and 2 illustrate various details of a loudspeaker or sound converter constructed in accordance with the invention.

An annular ring 1 is provided with three or more tangentially arranged projecting portions 2 which at their extremities carry radially arranged lugs 3, each lug having a circular opening 4. The front face 5 of the ring is fiat or planar and its exterior periphery 6 is preferably circular as shown. The centering device is preferably made of thin fibrous material such as cardboard which has a high degree of flexibility. Or it may be formed of any resilient non-magnetic metal. The cone diaphragm '7 has three slots or openings 8' near its small end, the arms 2-3 being inserted through these and cement or other adhesive being applied to the exterior surface 6 of ring 1 to secure diaphragm '7 securely thereto. If it is preferred to close-the small end of the cone by a transverse, circular end member 8, the fiat face 5 of the centering member may be also cemented to the rear face of member 8. As shown in Fig. 2, the exterior pole piece 9 of an electro-dynamic speaker carries three projecting portions 10 having tapped holes 11 therein. Screws 12 or other securing means are passed through the holes 4 into the holes 11 and thereby carry the voice coil 13 secured to coil form 14 centrally in the air gap 15. The large end of cone '7 may be supported within an aperture of framework 16 in any preferred manner.

What I claim and desire to secure by Letters Patent is:

1. In combination, a conical diaphragm having a voice coil secured to one end thereof, and provided near said end with at least three openings therein, a magnet having an annular air gap in which said coil is located, and means for centering said coil in said gap and also serving to close the small end of said conical diaphragm comprising a fiat member having a circular periphery seated against the interior surface of said diaphragm, said member being provided with a plurality of outwardly extending arms passing through the openings in said diaphragm, said arms being formed of resilient material and means engaging the end portions of said arms arranged to anchor them in fixed position.

2. In combination with the energizing coil of an acoustic converting device, means for yieldingly supporting said coil with respect to longitudinal motion and preventing motion thereof in a radial direction, comprising a flat annular disc composed of thin cardboard said disc having a plurality of tangentially extending arms terminating in radially shaped end portions, each end portion having an aperture and securing means passing through said apertures and arranged to immovably secure said end portions in fixed position.

FRITZ GABBERT. 

